CN101571691B - Electrostatic charging apparatus, and image forming assembly and image forming apparatus which employ the same - Google Patents

Abstract

An electrostatic charging apparatus, includes: an endless-shaped electrostatic charging belt having electrical conductivity, the electrostatic charging belt being arranged in a state of having a predetermined contact zone being in contact with a moving to-be-charged body and moving in the same direction as a moving direction of the to-be-charged body; and plural electrode members including at least a first electrode member and a second electrode member, the plural electrode members being provided inside the electrostatic charging belt, and the first and second electrode members being provided on both sides of the contact zone of the electrostatic charging belt in the moving direction thereof so as to press the electrostatic charging belt against the to-be-charged body and forming gaps thatpermit electric discharge between the to-be-charged body and the electrostatic charging belt, the gaps being adjacent to the respective sides of the contact zone of the electrostatic charging belt.

Description

Electrostatic charging device, image form assembly and image processing system

Technical field

The present invention relates to electrostatic charging device and adopt the image of this electrostatic charging device to form assembly and image processing system.

Background technology

Usually, in the image processing system that for example adopts xerography, electrostatic charging device is widely used in photoreceptor is carried out electrostatic charging.

As this electrostatic charging device, so-called contact-type electrostatic charging system is provided, thereby it is by making electrostatic charging roller or electrostatic charging band carry out electrostatic charging (for example referring to the Japanese Patent Publication No.H11-338221 (technical scheme of dealing with problems to photoreceptor with contacting as the photoreceptor that is recharged body, Fig. 1), Japanese Patent Publication No.H10-198123 (the technical scheme of dealing with problems, Fig. 1) and Japanese Patent Publication No.H10-186810 (inventive embodiment, Fig. 2)).

(technical scheme of dealing with problems Fig. 1) has disclosed a kind of like this pattern: removable electrostatic charging film is arranged to and contacts as the photoreceptor that is recharged body Japanese Patent Publication No.H11-338221; The shape limiting part that is applied with the electrostatic charging bias voltage on it is arranged on the inside of removable electrostatic charging film; And the adjacent position of contact area is formed with the minim gap that allows discharge between removable electrostatic charging film and photoreceptor.

In addition, (technical scheme Fig. 1) has disclosed a kind of like this pattern: removable electrostatic charging film is arranged to and contacts as the photoreceptor that is recharged body Japanese Patent Publication No.H10-198123; The electrostatic charging bias voltage is applied on the removable electrostatic charging film; And in removable electrostatic charging film, be provided with the small recess that allows towards the photoreceptor discharge.

Japanese Patent Publication No.H10-186810 (inventive embodiment, Fig. 2) disclosed a kind of like this pattern: the electrostatic charging device of multistage is arranged to contact with photoreceptor; The electrostatic charging device that moving direction along photoreceptor is positioned at hypomere carries out constant voltage control; And the electrostatic charging device to other sections carries out steady current control.

Summary of the invention

Technical purpose of the present invention provides a kind of like this electrostatic charging device and adopts the image of described electrostatic charging device to form assembly and image processing system: it can avoid the image deflects that caused by the charged electrostatically unevenness, and can reduce the discharge deterioration that is recharged body.

(1) according to an aspect of the present invention, a kind of electrostatic charging device is provided, comprise: ring-type electrostatic charging band, it has electric conductivity, described electrostatic charging band is arranged to have and the mobile state that is recharged the contacted predetermined contact area of body, and moves along the direction identical with the described moving direction that is recharged body; And a plurality of electrod assemblies, it comprises the first electrod assembly and the second electrod assembly at least, described a plurality of electrod assembly is arranged on the inside of described electrostatic charging band, and thereby described the first electrod assembly and described the second electrod assembly contact area that is arranged on described electrostatic charging band is squeezed in described being recharged on the body along the both sides of the moving direction of described electrostatic charging band with described electrostatic charging band, and described the first electrod assembly and described the second electrod assembly form respectively and allow in the described gap of discharging between body and the described electrostatic charging band that is recharged, and described each gap is respectively adjacent in the respective side of the contact area of described electrostatic charging band.

(2) such as above-mentioned (1) described electrostatic charging device, also comprise: bias voltage applying unit, its to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

(3) such as above-mentioned (2) described electrostatic charging device, wherein, described bias voltage applying unit applies described the first electrostatic charging bias voltage to described the first electrod assembly, and the AC component of described the first electrostatic charging bias voltage is equal to or less than the described surface potential of body that is recharged for the degree of tilt change point of described AC component.

(4) such as above-mentioned (2) or (3) described electrostatic charging device, wherein, described bias voltage applying unit applies described the second electrostatic charging bias voltage to described the second electrod assembly, and the AC component of described the second electrostatic charging bias voltage exceeds the described surface potential that is recharged body for the degree of tilt change point of described AC component and drop on can be described the second electrod assembly and described being recharged in the scope of carrying out Uniform Discharge between the body.

(5) as above-mentioned (1) in (4) each described electrostatic charging device, wherein, described the first electrod assembly and described the second electrod assembly are rotatable roller shape parts, described electrostatic charging band is stretched on the described roller shape parts.

(6) as above-mentioned (2) in (5) each described electrostatic charging device, wherein, described bias voltage applying unit has the operating environment judgment part for the decision operation environment, and described bias voltage applying unit changes the electrostatic charging bias voltage that is applied on each electrod assembly based on the judged result from described operating environment judgment part.

(7) as above-mentioned (1) in (6) each described electrostatic charging device, also comprise: extruder member (pressing component), thereby it pushes described a plurality of electrod assembly and forms described contact area and gap towards the described body that is recharged, described gap comprises anteroclusion gap and the rear interocclusal clearance that is close to along the described respective side that is recharged the moving direction of body with described contact area, and wherein said extruder member pushes described a plurality of electrod assembly so that described rear interocclusal clearance does not change substantially.

(8) according to a further aspect in the invention, provide a kind of image to form assembly, comprising: photoreceptor, it is as being recharged body; And as above-mentioned (1) in (7) each described electrostatic charging device, it is positioned to towards described photoreceptor, wherein said image forms assembly and is releasably attached on the image processing system main body.

(9) form assembly such as above-mentioned (8) described image, wherein, described electrostatic charging device also comprises bias voltage applying unit, described bias voltage applying unit to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

(10) according to another aspect of the invention, provide a kind of image processing system, comprising: photoreceptor, it is as being recharged body; And as above-mentioned (1) in (7) each described electrostatic charging device, it is positioned to towards described photoreceptor.

(11) such as above-mentioned (10) described image processing system, wherein, described electrostatic charging device also comprises bias voltage applying unit, described bias voltage applying unit to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

Can be controlled at independently respectively the discharge requirement of a plurality of region of discharges such as above-mentioned (1) described the present invention, can set thus the requirement that obtains the constant charge state and need not carry out unnecessary discharge.

The image deflects that caused by the charged electrostatically unevenness can be avoided such as above-mentioned (2) described the present invention, and the discharge deterioration that is recharged body can be reduced.

Can avoid unnecessary discharge occuring being adjacent to the gap that is recharged contact area between body and the electrostatic charging band and is positioned at the moving direction upstream side that is recharged body such as above-mentioned (3) described the present invention, therefore can increase the average potential that is recharged body.

Can carry out fully Uniform Discharge towards the surface that is recharged body being adjacent to the gap that is recharged contact area between body and the electrostatic charging band and is positioned at the moving direction downstream that is recharged body such as above-mentioned (4) described the present invention.Like this, the electrostatic charging current potential that can homogenising be recharged body.

It is stable with the discharge operation that is recharged between the body simultaneously can to realize the moving stability and the electrostatic charging band of electrostatic charging band such as above-mentioned (5) described the present invention.

Allow to select optimum electrostatic charging bias voltage according to the variation of operating environment such as above-mentioned (6) described the present invention.

Can further realize the electrostatic charging band and be recharged discharge operation stability between the body such as above-mentioned (7) described the present invention.

Image as above-mentioned (8) described the present invention allows to construct forms assembly: it can avoid the image deflects that caused by the charged electrostatically unevenness, and can reduce the discharge deterioration that is recharged body.

The image deflects that caused by the charged electrostatically unevenness can be avoided such as above-mentioned (9) described the present invention, and the discharge deterioration that is recharged body can be reduced.

Image processing system as above-mentioned (10) described the present invention allows to construct: it can avoid the image deflects that caused by the charged electrostatically unevenness, and can reduce the discharge deterioration that is recharged body.

The image deflects that caused by the charged electrostatically unevenness can be avoided such as above-mentioned (11) described the present invention, and the discharge deterioration that is recharged body can be reduced.

Description of drawings

Explain exemplary embodiment of the present invention based on following each figure, wherein:

Figure 1A is the key diagram that the exemplary embodiment summary of using electrostatic charging device of the present invention is shown, and Figure 1B is the key diagram of setting of AC component Vpp that the electrostatic charging bias voltage of electrostatic charging device is shown;

Fig. 2 is the key diagram that illustrates according to the total structure of the image processing system of exemplary embodiment 1;

Fig. 3 is the key diagram that illustrates according to the details of each color image forming section of exemplary embodiment 1;

Fig. 4 is the key diagram that illustrates according to the details of the electrostatic charging device of exemplary embodiment 1;

Fig. 5 is the key diagram of illustrative examples that the power supply unit of Fig. 4 is shown;

Fig. 6 A is the key diagram of establishing method that the AC component of electrostatic charging bias voltage is shown, and Fig. 6 B is the key diagram of establishing method that the DC component of electrostatic charging bias voltage is shown;

Fig. 7 A is the key diagram of the schematically illustrated electrostatic charging operating process of being undertaken by the electrostatic charging device according to exemplary embodiment 1, and Fig. 7 B is the key diagram of the schematically illustrated electrostatic charging mode of operation that is reached by this electrostatic charging device;

Fig. 8 A is the key diagram that is illustrated in the operation of carrying out according to (in the situation of high AC bias voltage) in the rear occlusal area of the electrostatic charging device of exemplary embodiment 1, and Fig. 8 B is the key diagram that is illustrated in the operation of carrying out according to (in the situation of low AC bias voltage) in the rear occlusal area of the electrostatic charging device of comparative example;

Fig. 9 is the key diagram that illustrates according to the illustrative examples of the electrostatic charging bias voltage setting control system of the electrostatic charging device of exemplary embodiment 2;

Figure 10 A is the key diagram that illustrates according to the illustrative examples of the surface potential Relations Among of the AC component Vpp1 of the electrostatic charging bias voltage of exemplary embodiment 2 and photoreceptor, and Figure 10 B is the key diagram that illustrates according to the illustrative examples of the surface potential Relations Among of the AC component Vpp2 of the electrostatic charging bias voltage of exemplary embodiment 2 and photoreceptor;

Figure 11 illustrates the process flow diagram that the electrostatic charging bias voltage that is undertaken by the electrostatic charging bias voltage setting control system shown in Fig. 9 is set the content of processing;

Figure 12 is the key diagram that illustrates according to another modified example embodiment of the power supply unit of the electrostatic charging device of exemplary embodiment 1 and 2;

Figure 13 is the key diagram that illustrates according to another modified example embodiment of the power supply unit of the electrostatic charging device of exemplary embodiment 1 and 2;

Figure 14 A and 14B are respectively the key diagram that illustrates according to another modified example embodiment of the electrostatic charging device of exemplary embodiment 1 and 2;

Figure 15 be illustrated in according in the electrostatic charging device of example 1 for the key diagram of the image deflects investigation result that a situation arises of different Vpp1/Vth and Vpp2/Vth value;

Figure 16 illustrates the value with Vpp2/Vth according to example 1 to be fixed as 1.3 and change the key diagram of the measurement result that the contact angle of the water on the photosensitive surface in the situation that the value of Vpp1/Vth discharges changes;

Figure 17 illustrates the value with Vpp2/Vth according to example 1 to be fixed as 1.3 and change the key diagram of the measurement result that the rate of wear on the photosensitive surface changes in the situation that the value of Vpp1/Vth discharges; And

Figure 18 is the key diagram of the illustrative examples of the reference table that adopts in the electrostatic charging device that is illustrated in according to example 2.

Embodiment

The summary of exemplary embodiment

Figure 1A shows the summary of the exemplary embodiment of using electrostatic charging device of the present invention.

In the figure, electrostatic charging device 2 is for being used for carrying out the charged electrostatically functional part as the photoreceptor that is recharged body 1, and for example consists of the component parts that the component parts of the image processing system that adopts xerography or formation are installed on the image processing system main body or form assembly from the image that this image processing system main body disassembles.

In this exemplary embodiment, electrostatic charging device 2 comprises: ring-type electrostatic charging band 3, it has electric conductivity, and is arranged as with respect to the mobile body 1 that is recharged and has the state of predetermined contact area and move along the direction identical with the moving direction that is recharged body 1; Bigeminal electrod assembly 4 (being 4a, 4b in this example), it is arranged on the inside of electrostatic charging band 3 and is positioned at electrostatic charging band 3 to be squeezed in respect to the both sides of be recharged body 1 contact area so that with electrostatic charging band 3 and is recharged on the body 1, and forms at the close position of the contact area of electrostatic charging band 3 and to allow be recharged the gap of discharging between body 1 and the electrostatic charging band 3; And bias voltage applying unit 5, it applies the electrostatic charging bias voltage Vc (Vc1, Vc2) that differs from one another to each electrod assembly 4 (4a, 4b), so that the AC component Vpp1 that is applied to the electrostatic charging bias voltage Vc1 on the electrod assembly 4a that is positioned at the moving direction upstream side that is recharged body 1 is at least less than the AC component Vpp2 that is applied to the electrostatic charging bias voltage Vc2 on the electrod assembly 4b that is positioned at the moving direction downstream that is recharged body 1.

In this technical scheme, be recharged body 1 and be the photoreceptor when being applied to the image processing system of xerography.Yet, the invention is not restricted to this photoreceptor, but comprise the multiple parts that are recharged such as dielectric material such as electrostatic recording apparatus.

In addition, electrostatic charging band 3 can be followed and is recharged body 1 rotation, perhaps can be driven by any other device.

In addition, bigeminal electrod assembly 4 (4a, 4b) is generally the rotatable roller shape parts of tensioning electrostatic charging band 3.Yet this not necessarily must be rotatable to electrod assembly, so this also can be fixed part to electrod assembly.Yet electrod assembly 4 needs to allow electrostatic charging band 3 to move, and need to have such shape (for example curve form): namely, form the gap that allows discharge at the close position of the contact area of electrostatic charging band 3.

In addition, bigeminal electrod assembly 4 (4a, 4b) need to be squeezed in electrostatic charging band 3 and be recharged on the body 1.Can satisfy this requirement by means of the biasing member such as spring etc.Needed extruding degree is so that can stably form as electrostatic charging band 3 and be recharged the gap of region of discharge between the body 1.

In addition, except electrod assembly 4 (4a, 4b), the accessory that can also arrange with tension part and be used for driving in the inside of electrostatic charging band 3.

In addition, the electrostatic charging bias voltage Vc that bias voltage applying unit 5 applies comprises various voltages, wherein is applied to the AC component Vpp1 of the electrostatic charging bias voltage Vc1 on electrod assembly (upstream side electrod assembly) 4a that is positioned at the moving direction upstream side that is recharged body 1 less than the AC component Vpp2 that is applied to the bias voltage on electrod assembly (downstream electrod assembly) 4b that is positioned at the moving direction downstream that is recharged body 1.This comprises a kind of like this pattern: namely, the electrostatic charging bias voltage Vc1 that is applied to upstream side electrod assembly 4a only has DC component Vdc, so the AC component A pp1 of electrostatic charging bias voltage Vc1 is zero.

When setting this electrostatic charging bias voltage Vc, in the anteroclusion district (adjacent position that is being recharged the contact area between body 1 and the electrostatic charging band 3 is positioned at the gap of the moving direction upstream side that is recharged body 1), the AC component Vpp1 of electrostatic charging bias voltage Vc1 is little.Like this, except there was variation in the electrostatic charging current potential, average potential increased.On the other hand, rear occlusal area (adjacent position that is being recharged the contact area between body 1 and the electrostatic charging band 3 is positioned at the gap in the moving direction downstream that is recharged body 1), the AC component Vpp2 of electrostatic charging bias voltage Vc2 is large.Like this, the electrostatic charging current potential that is recharged body 1 has expectation value and for uniformly.

In addition, in the anteroclusion district, the AC component Vpp1 of electrostatic charging bias voltage Vc1 is less than the AC component Vpp2 of the electrostatic charging bias voltage Vc2 in the rear occlusal area.Compare with rear occlusal area, this can reduce in the anteroclusion district by deteriorated (discharging product adhere to and wear and tear) that be recharged that discharge in the body 1 causes.

Next, in this exemplary embodiment, the preference pattern that is applied to the electrostatic charging bias voltage Vc1 on the upstream side electrod assembly 4a is: as shown in Figure 1B, bias voltage applying unit 5 upstream lateral electrode parts 4a applies following electrostatic charging bias voltage Vc1, and the AC component Vpp1 of described this electrostatic charging bias voltage Vc1 is equal to or less than the surface potential that is recharged body 1 for the degree of tilt change point M of AC component Vpp.

In addition, the preference pattern that is applied to the electrostatic charging bias voltage Vc2 on the electrod assembly 4b of downstream is: as shown in Figure 1B, bias voltage applying unit 5 downstream lateral electrode parts 4b applies following electrostatic charging bias voltage Vc2, and the surface potential that is recharged body 1 that the AC component Vpp2 of described electrostatic charging bias voltage Vc2 surpasses is for the degree of tilt change point M of AC component Vpp and drop on and can carry out in the usable range of Uniform Discharge to the surface that is recharged body 1.

In addition, the electrostatic charging bias voltage can be fixed.Select as another kind, the electrostatic charging bias voltage also can change according to operating environment.

In this pattern, bias voltage applying unit 5 can have can the decision operation environment the operating environment judgment part, and can change the electrostatic charging bias voltage Vc (Vc1, Vc2) that is applied on each electrod assembly 4 (4a, 4b) based on the judged result that obtains from the operating environment judgment part.Operating environment described here comprises such as environment around the temperature and humidity etc. and depends on uses the historical environment that lasts.

Below, with reference to the exemplary embodiment shown in the accompanying drawing the present invention is described in further detail.

Exemplary embodiment 1

-image processing system-

Fig. 2 shows the total structure according to the image processing system of exemplary embodiment 1.

In the figure, in image processing system such as the image forming portion 20 (20a to 20d) that is furnished with the four kinds of colors (being in this example yellow, magenta, blue-green (cyan) and black) that adopt xerography etc. along horizontal direction.Then, intermediate transfer belt 30 is arranged to allow at the position loopy moving relative with image forming portion 20.

Intermediate transfer belt 30 centers on a plurality of band idler rollers 31 to 34 and tensioning.Then, image forming portion 20 (20a to 20d) corresponding to intermediate transfer belt 30 with between idler roller 32 and 33 straight line portion and arrange.In addition, be furnished with primary transfer unit (for example primary transfer roller) 41 at intermediate transfer belt 30 corresponding to the back side of each image forming portion 20 (20a to 20d).Intermediate transfer belt 30 be provided with secondary transfer printing unit (for example secondary transfer roller) 42 with the relative part of idler roller 34.In addition, intermediate transfer belt 30 be provided with band cleaning unit 45 with the relative part of idler roller 31.

Then, in this exemplary embodiment, each color toner image primary transfer that primary transfer unit 41 will be formed by each image forming portion 20 successively is to intermediate transfer belt 30.Then, secondary transfer printing unit 42 with multiple transfer printing at the color toner image secondary transfer printing on the intermediate transfer belt 30 to the recording materials (not shown).The toner image that is subject to secondary transfer printing is directed to the fixation unit (not shown) together with recording materials.Then, for example by hot pressing with toner image to recording materials.

-image forming portion-

In this exemplary embodiment, as shown in Figures 2 and 3, each image forming portion 20 (20a to 20d) comprising: drum type photoreceptor 21, and it rotates along predetermined direction; Electrostatic charging device 22, it is arranged on the periphery of photoreceptor 21 and photoreceptor 21 is carried out electrostatic charging; Such as the exposing unit 23 of laser scanning device etc., it utilizes light that the electrostatic latent image of each color component is written on the photoreceptor 21 by electrostatic charging device 22 chargings; Developing cell 24, its utilize corresponding color toner so that each electrostatic latent image on the photoreceptor 21 as seen; And cleaning unit 25, it is arranged in the photoreceptor 21 downstream in the primary transfer zone relative with primary transfer unit 41, and the remaining toner on the cleaning photoreceptor 21.

Here, in this exemplary embodiment, four image forming portion 20 share exposing unit 23.Yet, the invention is not restricted to this structure.That is to say, such as arranging writing unit such as led array etc. corresponding to each photoreceptor 21.In addition, in Fig. 3, symbol Bm represents the light beam from exposing unit 23.

In this exemplary embodiment, can suitably select to comprise the photoreceptor 21 of Organophotoreceptor.Yet from the angle of wear prevention as far as possible, thereby photoreceptor is preferably at superficial layer and uses high hardness material to reach good wearing quality.

Obtain in the following manner the example of this photoreceptor 21: namely, will be layered in the drum basal body that is formed by materials such as aluminium for the bottom (glue-line) of Leakage prevention; Then, for example be that 1 μ m or less charge generating layers are layered on the bottom with thickness; Then, for example be that the charge transport layer of 15～40 μ m is layered on the charge generating layers with thickness.

Here, wearing face can be stacked on the charge transport layer layer by layer in case of necessity.In this case, this superficial layer for example can be for the a-SiN:H film or for not comprising a-C:H film or the a-C:H:F film of Si.Then, can reach per 1000 wear extenies that turn is 20nm or less wearing quality.

In addition, developing cell 24 for example can adopt two-component developing method.In this case, as shown in Figure 3, the two-component developing agent that is comprised of toner and carrier is housed in the developer container 241.Then, the developer roll 242 that be used for to transmit developer is arranged in towards the position of the relative opening of developer container 241 and photoreceptor 21.In addition, be useful on the layer-thickness restriction member 243 of restriction developer bed thickness in the periphery of developer roll 242.In addition, the rear side at developer roll 242 is provided with the stirring transfer member 244 that stirs in a looping fashion the transmission developer.

In addition, cleaning unit 25 for example can adopt the scraper plate cleaning method.In this case, as shown in Figure 3, scraper plate 252 is arranged on the edge of opening of cleaning container 251 against the sense of rotation of photoreceptor 21.Then, be provided with recovery transfer member 253 in the inside of cleaning container 251.Like this, scraper plate 252 strikes off the remaining toner on the photoreceptor 21.Then, reclaiming transfer member 253 is sent to the toner that reclaims in the used toner returnable (not shown).

In addition, in this exemplary embodiment, photoreceptor 21 and circumferential component one thereof turn to the form of handle box.Then, this handle box is releasably attached on the image processing system main body.Here, the circumferential component that turns to handle box with photoreceptor 21 one for example can be such pattern: namely, and integrated static charging device 22 and cleaning unit 25.Select as another kind, can adopt the pattern of independent integrated static charging device 22.In addition, can also adopt the pattern of integrated static charging device 22, cleaning unit 25 and developing cell 24.

-electrostatic charging device-

Next, will the electrostatic charging device 22 that adopt in this exemplary embodiment be described in further detail.

Fig. 4 schematically shows the structure of the electrostatic charging device 22 that adopts in this exemplary embodiment.

In the figure, electrostatic charging device 22 comprises: ring-type electrostatic charging band 50, and it has electric conductivity; A pair of bias voltage applies roller 51 and 52, around its tensioning electrostatic charging band 50 and the electrostatic charging bias voltage is applied to this bias voltage is applied on the roller; Electrostatic charging container 55, it is used for accommodating electrostatic charging band 50 and bias voltage applies roller 51 and 52; And pressing mechanism 56, it is used for towards photoreceptor 21 sides bias voltage being applied roller 51 and 52 and pushes.

Here, the electrostatic charging band 50 that adopts is by conductive agent being distributed in the materials such as PVdF, polyamide, polyimide, polyetherimide, elastic body PVdF, polyester, polycarbonate, polyolefin, PEN, PEK, PES, PPS, PFA, ETFE, CTFE so that surface resistivity is adjusted to 10 ⁶～10 ⁸Ω/ etc. and the film of 20～100 μ m that form.

In addition, each bias voltage applies the electroconductive resin material 54 that roller 51 and 52 runs through for the axle core components 53 that is made of conductive metal.Here, electroconductive resin material 54 can be made of the various materials that comprise electric conductivity foam polyester.

In addition, in pressing mechanism 56, electroconductive resin bearing (not shown) is assembled on the bearings parts 57, then the electroconductive resin bearing rotatably supports the axle core components 53 that bias voltage applies roller 51 and 52, and then extrusion spring 58 bias voltage bearings parts 57 are in order to apply roller 51 and 52 towards photoreceptor 21 1 sides extruding bias voltage.

The numerical value of the extruding force of extrusion spring 58 is selected as follows.That is to say that electrostatic charging band 50 and photoreceptor 21 apply at bias voltage has contact area m between roller 51 and 52.Then, form anteroclusion gap g1 and the rear interocclusal clearance g2 that allows discharge between electrostatic charging band 50 and photoreceptor 21 in the both sides of contact area m.At this moment, as hereinafter described, apply the magnitude relationship of the electrostatic charging bias voltage on roller 51 and 52 from being applied to bias voltage, it is may guiding discharge unstable to stride across contact area m is positioned at the rear interocclusal clearance g2 in downstream along the moving direction of photoreceptor 21 change.Therefore, need in the scope of not change of rear interocclusal clearance g2, to select at least the numerical value of extruding force.

In this example, pressing mechanism 56 applies roller 51 and 52 to this to bias voltage and applies roughly the same extruding force.Like this, except bias-removing applies the weight of roller 51 and 52, (2.45～3.43N) etc. power is pushed the end that bias voltage applies roller 51 and 52 with 250～350gf.

-electrostatic charging bias voltage-

In addition, power supply unit 60 applies roller 51 with each bias voltage of electrostatic charging device 22 and is connected with being connected.Then, power supply unit 60 is supplied with electrostatic charging bias voltage Vc1 and the Vc2 that differs from one another.

Fig. 5 shows the example of power supply unit 60.

In the figure, power supply unit 60 comprises: DC power supply 61, and it is used for supplying with the DC component Vdc of electrostatic charging bias voltage Vc (Vc1, Vc2); AC power supplies 62, itself and DC power supply 61 are connected in series, and apply the AC component Vpp1 (peak-to-peak voltage) that roller 51 is supplied with electrostatic charging bias voltage Vc (Vc1) to the bias voltage that the moving direction along photoreceptor 21 is positioned at upstream side; And AC power supplies 63, itself and DC power supply 61 are connected in series, and apply the AC component Vpp2 (peak-to-peak voltage) that roller 52 is supplied with electrostatic charging bias voltage Vc (Vc2) to the bias voltage that the moving direction along photoreceptor 21 is positioned at the downstream.

In the setting of this exemplary embodiment, be applied to a bias voltage and apply the AC component Vpp1 of electrostatic charging bias voltage Vc1 of roller 51 less than the AC component Vpp2 that is applied to another bias voltage and applies the electrostatic charging bias voltage Vc2 of roller 52.

More specifically, Fig. 6 A shows the AC component Vpp that is applied to an electrostatic charging bias voltage Vc on the electrostatic charging roller and utilizes this bias voltage and relation between the surface potential Vh of the photoreceptor 21 that charged.

Find out that from this figure when the AC component Vpp of electrostatic charging bias voltage Vc increased, the surface potential Vh of photoreceptor 21 almost increased linearly, then is tending towards saturated.That is to say that the increase trend of photoreceptor 21 surface potential Vh dies down after surpassing the degree of tilt change point M corresponding to saturation point.

At this moment, when the AC component Vpp of electrostatic charging bias voltage Vc was equal to or less than degree of tilt change point M, it was inhomogeneous on the surface of photoreceptor 21 electrostatic charging to occur easily.That is to say, when the AC component Vpp of electrostatic charging bias voltage Vc is in the level that exceeds a little degree of tilt change point M, carry out non-homogeneous discharge to the surface of photoreceptor 21, thereby easily by non-homogeneous discharge generation white point and look (deceiving) point.Yet, when the AC component Vpp of electrostatic charging bias voltage Vc exceeds predetermined value, carry out Uniform Discharge to the surface of photoreceptor 21.This can reduce the above-mentioned drawback (producing white point and look (deceiving) point) that is caused by non-homogeneous discharge.However, also can generate discharging product, then discharging product is attached on photoreceptor 21 surfaces easily.In this case, when when suppressing as much as possible angle that discharging product adheres to and select the AC component Vpp of electrostatic charging bias voltage Vc, should select such numerical value: namely, the threshold level of the necessary minimum value in realizing the usable range of discharging to the surface uniform of photoreceptor 21.

In a word, be applied to the AC component Vpp1 that bias voltage applies the electrostatic charging bias voltage Vc 1 on the roller 51 and be chosen as the numerical value that is equal to or less than degree of tilt change point M, be chosen as numerical value above degree of tilt change point M and be applied to AC component Vpp2 that bias voltage applies the electrostatic charging bias voltage Vc2 on the roller 52, and be preferably the numerical value of the floor level of realizing Uniform Discharge.

On the other hand, Fig. 6 B shows the DC component Vdc that is applied to an electrostatic charging bias voltage Vc on the electrostatic charging roller and utilizes this bias voltage and relation between the surface potential Vh of the photoreceptor 21 that charged.

Find out that from this figure the DC component Vdc of the surface potential Vh of photoreceptor 21 and electrostatic charging bias voltage Vc is roughly linear.Like this, select numerical value corresponding to electrostatic charging target current potential for the DC component Vdc of electrostatic charging bias voltage Vc.

As a result, electrostatic charging bias voltage Vc1 and Vc2 select as follows.

Vc1＝Vdc+Vpp1(Vpp1＜Vpp2)

Vc2＝Vdc+Vpp2

In addition, the application time of the electrostatic charging bias voltage Vc (Vc1, Vc2) of the 100 definite power supply units 60 of the control module shown in Fig. 4 and DC component Vdc and the AC component Vpp (Vpp1, Vpp2) of electrostatic charging bias voltage.

Here, thus for example carry out in advance DC component Vdc and the AC component Vpp (Vpp1, Vpp2) that initializing set is set electrostatic charging bias voltage Vc by the input operation of guidance panel 110.

The operation of-electrostatic charging device-

Next, with the electrostatic charging operating process of explanation according to the electrostatic charging device 22 of this exemplary embodiment.

Shown in Fig. 2 and Fig. 7 A, in each image forming portion 20 (20a to 20d), 22 pairs of photoreceptors of electrostatic charging device 21 carry out electrostatic charging.

At this moment, electrostatic charging bias voltage Vc1=Vdc+Vpp1 is applied to the bias voltage that is positioned at upstream side along the moving direction of photoreceptor 21 applies on the roller 51, thereby in anteroclusion gap g1 (the regional I among Fig. 7 A), discharge.

At this moment, Vpp1 is set as the degree of tilt change point M that is equal to or less than as shown in Figure 6A.Like this, do not carry out sufficient electrostatic charging at regional I.Yet because anteroclusion gap g1 narrows down gradually, therefore photoreceptor 21 lip-deep average electrostatic charging current potentials increase shown in Fig. 7 B.As a result, produce the surface potential corresponding with the frequency of electrostatic charging bias voltage Vc.Afterwards, do not discharge among the contact area m between electrostatic charging band 50 and photoreceptor 21 (the regional II among Fig. 7 A).Like this, shown in Fig. 7 B, the amplitude of the surface potential of photoreceptor 21 remains unchanged and then enters rear interocclusal clearance g2 (the regional III among Fig. 7 A and the 7B).

In rear interocclusal clearance g2, electrostatic charging bias voltage Vc2=Vdc+Vpp2 is applied to the bias voltage that is positioned at the downstream along the moving direction of photoreceptor 21 applies on the roller 52, thereby discharge.

At this moment, rear interocclusal clearance g2 broadens gradually.Like this, shown in Fig. 7 B, appear at rear interocclusal clearance g2 near the large amplitude of the surface potential of contact area m along with widening of gap equalization.Then, the surface potential at the terminal part photoreceptor 21 of rear interocclusal clearance g2 (regional III) becomes even.

This is described as follows.For example shown in Fig. 8 A, the AC component Vpp2 of electrostatic charging bias voltage Vc2 exceeds degree of tilt change point M as shown in Figure 6A, and is in the sufficiently high level (in the situation of high AC bias voltage) for Uniform Discharge.Like this, near effective region of discharge A even extend to the terminal part of rear interocclusal clearance g2.This will be suppressed at gap variation and the inhomogeneous impact of resistance of the terminal part of rear interocclusal clearance g2, therefore will reduce significantly non stationary discharge zone B.

For this point, for example shown in Fig. 8 B, in the conceptual comparative example in the non-homogeneous region of discharge after the AC component Vpp2 of electrostatic charging bias voltage Vc2 is equal to or less than degree of tilt change point M as shown in Figure 6A or is in degree of tilt change point M and then, effective region of discharge A ' of rear interocclusal clearance g2 narrows down, and causes the contiguous position of terminal part of rear interocclusal clearance g2 to become non stationary discharge zone B '.Like this, the gap variation in the terminal part of rear interocclusal clearance g2 and resistance is inhomogeneous to have large impact, therefore causes occurring the white point that electrostatic charging is inhomogeneous or fault produces and look (deceiving) point that cause owing to non stationary discharge.

Here, the non stationary discharge zone among the g1 of anteroclusion gap is positioned at the upstream of the beginning of effective region of discharge.Like this, impact can not appear.

As mentioned above, in this exemplary embodiment, in the g1 of the anteroclusion gap of electrostatic charging band 50, fully realized increasing the function of the average surface current potential of photoreceptor 21.On the other hand, in the rear interocclusal clearance g2 of electrostatic charging band 50, fully realized the function of the surface potential of equalization and unification photoreceptor 21.

That is to say, the anteroclusion gap g1 of electrostatic charging band 50 and the electrostatic charging function of rear interocclusal clearance g2 are separated.Then, in the g1 of anteroclusion gap, select to obtain the interior minimum value Vpp1 of scope of expectation electrostatic charging voltage.On the contrary, in rear interocclusal clearance g2, select not occur the interior minimum value Vpp2 of scope of image deflects (white point and look (deceiving) point).

Especially, in the g1 of anteroclusion gap, the AC component Vpp1 of electrostatic charging bias voltage Vc1 is set as little numerical value.The pattern that applies the AC component Vpp2 identical with rear interocclusal clearance g2 with interocclusal clearance g1 is forward compared, and this will reduce deteriorated (adhesion amount of discharging product and the wear extent) on photoreceptor 21 surfaces that caused by discharge.

Exemplary embodiment 2

Fig. 9 shows the electrostatic charging device 22 that adopts in the image processing system according to exemplary embodiment 2.

In this exemplary embodiment, be similar to exemplary embodiment 1, in electrostatic charging device 22, electrostatic charging bias voltage Vc1=Vdc+Vpp1 is applied to the bias voltage that is positioned at upstream side along the moving direction of photoreceptor 21 applies on the roller 51.In addition, electrostatic charging bias voltage Vc2=Vdc+Vpp2 being applied to the bias voltage that is positioned at the downstream along the moving direction of photoreceptor 21 applies on the roller 52.

Then, be chosen as corresponding to the degree of tilt change point M (seeing Fig. 6 A) in the surface potential change curve of photoreceptor 21 for the AC component of the electrostatic charging bias voltage Vc1 numerical value with Vpp 1.On the other hand, for the AC component of electrostatic charging bias voltage Vc2 with the numerical value of Vpp2 be chosen as in the surface potential change curve that exceeds photoreceptor 21 degree of tilt change point M and corresponding to the lower limit (evenly electrostatic charging zone lower-limit point) of the usable range that can realize Uniform Discharge.

Yet, be according to the electrostatic charging device 22 of this exemplary embodiment difference with the electrostatic charging device 22 of exemplary embodiment 1: considering environmental information and using in the situation of historical information and set electrostatic charging bias voltage Vc (Vc1, Vc2).

That is to say that as shown in Figure 9, the essential structure of electrostatic charging device 22 is almost identical with exemplary embodiment 1.Yet the setting processing to electrostatic charging bias voltage Vc of being undertaken by control module 100 is different from exemplary embodiment 1.

In the figure, control module 100 comprises: Vdc control section 111, and it is used for the DC component Vdc of control electrostatic charging bias voltage Vc; Vpp control section 112, it is used for the AC component Vpp (Vpp1, Vpp2) of control electrostatic charging bias voltage Vc; And reference table 113, when determining the AC component Vpp (Vpp1, Vpp2) of electrostatic charging bias voltage Vc, use this reference table.

Then, control module 100 obtains: from the environmental information of environmental sensor 101 one of (in the temperature and humidity at least); From the use historical information of using historical memory 102 (as operation time of the use history of electrostatic charging device 22, convert the quantity etc. of the paper that is formed with image of the reference dimension of image processing system to); And from the input operation information of guidance panel 110.

Here, thus when initializing set, for example according to the input operation by guidance panel 110 the DC component Vdc of electrostatic charging bias voltage Vc is set as predetermined default value corresponding to predetermined electrostatic charging level.

Next, the example of the reference table 113 that adopts in this exemplary embodiment is described with reference to Figure 10 A and 10B.

The appropriate value of the AC component Vpp (Vpp1, Vpp2) of electrostatic charging bias voltage Vc (Vc1, Vc2) depends on to a great extent the environmental baseline of photoreceptor 21 and uses historical conditions.Like this, in this exemplary embodiment, prepare in advance for according to the environmental baseline of photoreceptor 21 with select the reference table 113 of optimum electrostatic charging bias voltage Vc with the variation of historical conditions.

At first, discussion is selected as the degree of tilt change point M (seeing Fig. 6 A) of the AC component Vpp 1 of electrostatic charging bias voltage Vc1.Shown in Figure 10 A, degree of tilt change point M is along with low temperature and low humidity environment Ya (for example, 10 ℃/10%), ambient temperature and moisture environment Yb (for example, 22 ℃/50%) and hot and humid environment Yc (for example, 28 ℃/85%) and change.Like this, need to change Vpp1 according to environmental baseline.In addition, under every kind of environment, degree of tilt change point M is also along with photographic layer thickness (d:d ₀＜d ₁＜d ₂＜d ₃＜d ₄＜d ₅＜d ₆) and change.Like this, for example when photoreceptor 21 with use historical relevant and deteriorated so that photographic layer thickness d owing to wear and tear when reducing, need to be according to changing Vpp1 with historical conditions.

From this viewpoint, for the degree of tilt change point M that is selected as Vpp 1, can measure in advance itself and environmental baseline and use relation between the historical conditions (for example, as the photographic layer thickness d that uses historical function), then can prepare reference table 113 based on this.

In addition, the below is selected as discussion the lower limit (evenly electrostatic charging zone lower-limit point) of usable range of the Uniform Discharge realized of the AC component Vpp2 of electrostatic charging bias voltage Vc2.Shown in Figure 10 B, evenly electrostatic charging zone lower-limit point also depends on environmental baseline (Ya, Yb, Yc) and uses historical conditions (for example, with the history-sensitive photographic layer thickness d of use).Like this, for the even electrostatic charging zone lower-limit point that is selected as Vpp2, can measure in advance itself and environmental baseline and use relation between the historical conditions (for example, as the photographic layer thickness d that uses historical function), then can prepare reference table 113 based on this.

Here, in Figure 10 A and 10B, the symbol V on the vertical axes ₀～V ₃Scalar value (the V of expression AC component ₀＜V ₁＜V ₂＜V ₃).

In addition, in Figure 10 A and 10B, usually at the degree of tilt change point M that is selected as Vpp1 and be selected as between the even electrostatic charging zone lower-limit point of Vpp2 and non-homogeneous region of discharge occurs.Like this, concern and such trend can occur by Vpp2＞Vpp1 although satisfy as a rule: namely, the difference increase when photographic layer thickness d increases between Vpp1 and the Vpp2, on the contrary the difference between Vpp1 and the Vpp2 reduces when photographic layer thickness d reduces.

Next, the electrostatic charging bias voltage in the explanation control module 100 is set processing.

Figure 11 illustrates the electrostatic charging bias voltage to set the process flow diagram of processing.

As shown in the drawing, at first, the Vdc control section 111 of control module 100 is set as the default value that limits in advance with the DC component Vdc of electrostatic charging bias voltage Vc.

Then, the Vpp control section 112 of control module 100 detects from the environmental information of environmental sensor 101 with from the use historical information of using historical memory 102 (as operation time of the use history of electrostatic charging device 22, convert the quantity etc. of the paper that is formed with image of the reference dimension of image processing system to), thereby judges environmental rating (low temperature and low humidity environment Ya or ambient temperature and moisture environment Yb or hot and humid environment Yc) based on environmental information.In addition, Vpp control section 112 is based on the degradation of the initial photographic layer that uses historical information estimation photoreceptor 21, thus definite photographic layer thickness d.

Under this state, the Vpp control section of control module 100 112 search reference table 113 as shown in Figure 9, thus set Vpp1 and the Vpp2 of electrostatic charging bias voltage Vc based on the environmental rating of judging and photographic layer thickness d.

As mentioned above, in this exemplary embodiment, even when environmental baseline and the variation of use historical conditions, also can in the situation of considering these conditions, set the AC component Vpp (Vpp1, Vpp2) of electrostatic charging bias voltage Vc.This can provide the advantage that is better than exemplary embodiment 1: namely, keep gratifying electrostatic charging performance according to environmental baseline with historical conditions.

In addition, in this exemplary embodiment, set changeably the AC component Vpp (Vpp1, Vpp2) of electrostatic charging bias voltage Vc according to environmental baseline and use historical conditions.Yet, can and use arbitrary condition in the historical conditions set changeably the AC component Vpp of electrostatic charging bias voltage Vc based on environmental baseline.Select as another kind, under the thicker pattern of photographic layer thickness d, can consider at the same time environmental baseline and use the AC component Vpp that sets changeably electrostatic charging bias voltage Vc in the situation of historical conditions, and under the thinner pattern of photographic layer thickness d, can in the situation of only considering environmental baseline, set changeably the AC component Vpp of electrostatic charging bias voltage Vc.This is because use the little cause of correlativity of historical conditions under latter's pattern.

In this exemplary embodiment, prepare reference table 113 in advance, thereby then set changeably the AC component Vpp of electrostatic charging bias voltage Vc by searching for this table.Yet, the invention is not restricted to this.For example, the discharge charge amount in the photographic layer can be measured, thereby photographic layer thickness d can be detected.Then, can set changeably the AC component Vpp of electrostatic charging bias voltage Vc based on detected information.

The modified example embodiment of power supply unit

In exemplary embodiment 1 and 2, the power supply unit 60 of electrostatic charging device 22 has adopted the pattern shown in Fig. 4 or 9.Yet, the invention is not restricted to this.For example, as shown in figure 12, power supply unit can comprise: DC power supply 61, and it is used for supplying with the DC component Vdc of electrostatic charging bias voltage Vc; AC power supplies 64, it applies between roller 51 and 52 at DC power supply 61 and each bias voltage and is connected in series, and supplies with the AC component Vpp of electrostatic charging bias voltage Vc; And resistive element 65, its bias voltage that is inserted in AC power supplies 64 and anteroclusion side applies between the roller 51, and reduces the AC component Vpp from AC power supplies 64.

In addition, as shown in figure 13, another modified example embodiment of the power supply unit 60 of electrostatic charging device 22 comprises: DC power supply 61, and it is used for supplying with the DC component Vdc of electrostatic charging bias voltage Vc; AC power supplies 63, its bias voltage in DC power supply 61 and rear interlock side applies between the roller 52 and is connected in series, and supplies with the AC component Vpp2 of electrostatic charging bias voltage Vc; And auxiliary DC power supply 66, its bias voltage in DC power supply 61 and anteroclusion side applies between the roller 51 and is connected in series, and supplies with auxiliary DC component Vdc1.Under this pattern, the bias voltage to the anteroclusion side does not apply roller 51 supply AC components.

The modified example embodiment of electrostatic charging device

In exemplary embodiment 1 and 2, be provided with a pair of bias voltage in the inside of electrostatic charging band 50 and apply roller 51 and 52.Yet, the invention is not restricted to this structure.For example, shown in Figure 14 A, can the pressure-producing part 71 that be made of resilient material be set in the inside of electrostatic charging band 50.Then, can in the two sides of pressure-producing part 71, to photoreceptor 21 sides electrod assembly 72 and 73 be set, in this case can be from power supply unit 60 to electrod assembly 72 and 73 apply electrostatic charging bias voltage Vc1 and Vc2.

Here, in this example, for electrod assembly 72 and 73 and photoreceptor 21 between form to allow anteroclusion gap g1 and the rear interocclusal clearance g2 of discharge, electrod assembly 72 and 73 shape need to have curved shape, perhaps select as another kind of, pressure-producing part 71 needs by this way flexibly clamping electrostatic charging band 50 with photoreceptor 21: namely, form contact area between photoreceptor 21 and electrod assembly 72 and 73.

In addition, in exemplary embodiment 1 and 2, electrostatic charging band 50 rotates along with the rotation of photoreceptor 21.Yet, the invention is not restricted to this structure.For example, as shown in Figure 14B, can at the arranged outside driven roller 81 of electrostatic charging band 50, can the driving help roll 82 that come clamping electrostatic charging band 50 against electrostatic charging band 50 relatively be set with driven roller 81 simultaneously.Then, can drive driven roller 81 by driving motor 83, thereby can utilize external motivating force to drive electrostatic charging band 50.

Example

Example 1

By adopting the image processing system structure example 1 according to exemplary embodiment 1.

The condition of-image processing system-

In the image processing system according to example 1, the processing speed of photoreceptor is 220mm/sec, and the electrostatic charging current potential of photosensitive surface is-700V, and the exposed portion current potential of exposing unit is-300V.In addition, be that 6kHz and dutycycle are that the development bias voltage that 60% square wave is added to-produces on the DC component of 560V is applied on the developer roll of developing cell with amplitude (peak-to-peak voltage) for 1.0kV, frequency, thereby form toner image.This toner image is transferred on the intermediate transfer belt, then is transferred on the recording materials, then carry out photographic fixing by fixation unit.

Here, the toner that adopts is produced by emulsion polymerisation process, and has the volume average particle size of the 5.8 μ m that measured by coulter counter (being made by Coulter Incorporation).The toner particle diameter is not necessarily limited to this value, but can be 3～7 μ m.Utilize shape coefficient to express the shape of toner-particle, wherein this shape coefficient is to use image analyzer Luzex 3 (being made by NIRECO Corporation) to by optical microscope (MicroPhoto-FXA; Made by NIKON Corporation) enlarged photograph of the toner-particle that obtains carries out graphical analysis and calculates according to following formula.

Shape coefficient=(the absolute maximum length of toner diameter) ²/ toner projected area * (I/4) * 100

Express this toner shape coefficient by the projected area of toner-particle and the ratio between its circumscribed circle area.In the situation that is complete spheroid, the numerical value of shape coefficient is 100.When shape was out of shape, this numerical value increased.A plurality of toner-particles are calculated shape coefficient, and its mean value is used as typical value.In this example, the employing shape coefficient is 130～140 toner.Be that the inorganic particles such as silicon dioxide and titania (external additive) of 10～150nm externally adds in the toner with the mean grain size of appropriate amount.Here, adopt in this example above-mentioned developer.Yet the present invention is not necessarily limited to this.That is to say the crushed toner that can adopt tradition to use.In addition, adopting by mean grain size is the carrier that the ferrite bean of 35 μ m consists of.

-electrostatic charging device-

Electrostatic charging band: conductive agent is distributed among the PVdF (the contact angle θ of water: about 90 spend) so that surface resistivity is adjusted to 10 ⁶Then Ω/ forms this material the shape that thickness is the film of 45 μ m, and adopts this film.

Bias voltage applies roller: the external diameter that the axle core components that use is made of conductive metal runs through is Electric conductivity foam polyester material.

Pressing mechanism: the power extruding bias voltage of the 275gf of extrusion spring utilization except bias-removing applies roller weight applies an end of roller.

In this example, a situation arises to investigate image deflects (fault) by the numerical value that changes Vpp1-Vpp2, thereby obtain result as shown in figure 15.

In the figure, symbol Vth represents the point (corresponding to degree of tilt change point M) that the degree of tilt of Vpp-Vh (surface potential of photoreceptor) changes.Its value is 1.42kVpp.

As can be seen from this figure, when utilizing enough Vpp2 to discharge, defective can not appear.Apply under the pattern that roller is connected with the bias voltage of anteroclusion side replacing AC power supplies with the DC power supply in addition, (pattern shown in Figure 13/DC component (DC)=-1.5kV), obtain equally similar result.

Next, be fixed as 1.3 and change in the situation of value of Vpp1/Vth that the contact angle of water changes after the investigation discharge in the value with Vpp2/Vth.The result who obtains as shown in figure 16.

At this moment, investigation charged electrostatically impact under the state that removes cleaning unit, developing cell, intermediate transfer belt and primary transfer unit.Photoreceptor rotation 30 is measured contact angle after turning before the discharge beginning and after the discharge beginning.Then, suppose that the difference with the rear measured contact angle that obtains of discharge beginning is relevant with the adhesion amount of discharging product before the discharge beginning.Here, the AC frequency of electrostatic charging bias voltage is 1440Hz.

This result shows: when reducing Vpp1, can suppress the adhesion amount of discharging product.

Here, the symbol among the figure represents to adopt the data of the comparative example of an electrostatic charging roller, and shows the contact angle difference of water in the situation of Vpp1/Vth=1.3 (Vth=1.85kVpp).In addition, symbol △ represent with DC component (DC)=-bias voltage that 1.5kV is applied to the anteroclusion side applies the data of the pattern on the roller.

Similarly, image processing system is moved test, thus the difference of the rate of wear of investigation photoreceptor.

Equally at this moment, the value with Vpp2/Vth is fixed as 1.3.Service condition is as follows.

Electrostatic charging bias voltage: Vdc=-720V, Vpp1/Vth=1.0,1.15,1.3, Vpp2/Vth=1.3

Frequency: 1440Hz

Processing speed: 220mm/sec

The printing number of every subjob: 100, print total number: 30,000

Image area ratio: 5%

Operating environment: 22 ℃/50%

Figure 17 shows the photoreceptor rate of wear of this moment.

Or the angle from wearing and tearing when reducing Vpp1, can suppress the adhesion amount of discharging product.

Example 2

This example is for realizing the enforcement according to the image processing system of exemplary embodiment 2.Figure 18 shows the instantiation for the reference table of the Vpp1 that determines electrostatic charging device and Vpp2.

Thereby the electrostatic charging device of this example is set Vpp1 and the Vpp2 of electrostatic charging device changeably according to environmental baseline and use historical conditions based on the reference table shown in Figure 18.

The following describes the reference table shown in Figure 18.

At first, the photoreceptor that adopts in this example is as follows.

In this photoreceptor, photographic layer is layered in such as on the drum type matrixes such as aluminium.Photographic layer has charge generating layers and is positioned at the charge transport layer of top layer.Then, be formed with the bottom of Leakage prevention at orlop.

The following describes the example of each layer.

Bottom:

Zinc paste (SMZ-017N: made by TAYCA Corporation) and the toluene of 500 weight portions of 100 weight portions are mixed mutually.Then, add the silane coupling agent (A1100: by Nippon Unicar Co., Ltd makes) of 2 weight portions, then stirred 5 hours.Afterwards, vacuum distillation toluene.Then, under 120 ℃ condition, carry out baking in 2 hours.Effects on surface is processed zinc paste and is carried out the result that fluorescent X-ray analysis obtains and show that element silicon intensity is 1.8 * 10 of zinc element-intensities ^-4With the surface treatment zinc paste of 35 weight portions, 15 weight portions as the piece type polyurethane Sumidur 3175 of hardening agent (by Sumitomo-Bayern Urethane Co., the Ltd manufacturing), the butyral resin BM-1 of 6 weight portions is (by Sekisui Chemical Co., Ltd makes) and the 2-butanone of 44 weight portions mix, then use

Beaded glass carry out 2 hours dispersion treatment by sand mill, thereby obtain dispersion liquid.Then, with adding in the dispersion liquid that obtains as two lauric acid dioctyl tins of catalyzer and the Tospearl 130 of 17 weight portions (by GE Toshiba Silicones Co., Ltd makes) of 0.005 weight portion, thereby obtain the bottom coating fluid.By dip coating with this coating fluid be applied to by

The drum type matrix that consists of of aluminum on.Then, under 160 ℃, carry out 100 minutes drying sclerosis, thereby obtain having the bottom of 20 μ m thickness.

Charge generating layers:

The electric charge generating material that adopts is the gallium chloride phthalocyanine.The gallium chloride phthalocyanine of 15 weight portions, the vinyl chloride-vinyl acetate copolymer resin of 10 weight portions (VMCH, by UnionCarbide Japan Co., Ltd makes) and the normal butyl alcohol of 300 weight portions are mixed.Then, the dispersion treatment of utilizing sand mill this potpourri to be carried out 4 hours.Then, by dip coating the dispersion liquid that obtains is applied on the bottom, then carries out drying, thereby obtain to have the charge generating layers of 0.2 μ m left and right sides thickness.

Charge transport layer:

The fluorine family graft copolymer as dispersing aid of the polyflon particle of 8 weight portions and 0.16 weight portion is fully stirred and is mixed in the toluene of the tetrahydrofuran of 49 weight portions and 21 weight portions, thereby prepare the polyflon particle suspension liquid.

Then, N with 40 weight portions, N '-two (3-tolyl)-N, the bisphenol Z polycarbonate resin of N '-diphenylbenzidine and 60 weight portions (molecular weight: 40,000) fully dissolve and be mixed in the toluene of the tetrahydrofuran of 231 weight portions and 99 weight portions.Afterwards, above-mentioned polyflon particle suspension liquid is added to wherein, then stir and mix.Then, use and to be provided with the high pressure homogenisers that runs through the die cavity chamber with meticulous passage (by Nanomizer Co., Ltd makes, trade name: LA-33S), repeat four times and boost to 500kgf/cm ²Dispersion treatment, thereby prepare the polyflon particle dispersion.Then, by dip coating the coating fluid that obtains is applied on the charge generating layers, then carries out drying, thereby form the charge transport layer with 29 μ m left and right sides thickness.

In addition, in Figure 18, the grade of environmental baseline is as follows.

Low temperature and low humidity environment Ya:10 ℃/10%

Ambient temperature and moisture environment Yb:22 ℃/50%

Hot and humid environment Yc:28 ℃/85%

In addition, in Figure 18, the photographic layer thickness on the transverse axis represents the thickness of charge transport layer.This corresponding to the use of photoreceptor history-sensitive deteriorated (being mainly wearing and tearing) degree.Here, can learn that degree of tilt change point M and even electrostatic charging zone lower-limit point are subjected to the impact of the bed thickness of bottom and charge generating layers hardly.

In addition, in this example, will be elected to be Vpp1 corresponding to the AC component of the electrostatic charging bias voltage of degree of tilt change point M, and the AC component that will be in the electrostatic charging bias voltage of even electrostatic charging zone lower-limit point is elected to be Vpp2.In Figure 18, vertical axes is illustrated under the various environmental baselines for the photographic layer thickness, corresponding to the AC component (Vpp1) of the electrostatic charging bias voltage of degree of tilt change point M be in the AC component (Vpp2) of the electrostatic charging bias voltage of even electrostatic charging zone lower-limit point.

As can be seen from Figure 18, increase along with the variation from the low temperature and low humidity environment to hot and humid environment corresponding to the AC component (vpp1) of the electrostatic charging bias voltage of degree of tilt change point M and the AC component (Vpp2) that is in the electrostatic charging bias voltage of even electrostatic charging zone lower-limit point.In addition, each AC component is tending towards increasing along with the increase of photographic layer thickness under every kind of environment, otherwise reduces along with the minimizing of photographic layer thickness.

In addition, be tending towards reducing along with the minimizing of photographic layer thickness (be equal to or less than 15 μ m time difference value and be approximately 0) in the difference between Vpp1 and the Vpp2 under every kind of environment, otherwise increase along with the increase of photographic layer thickness.

Like this, in this example, can judge environmental baseline and use historical conditions based on environmental information with historical information, then can search for reference table as shown in figure 18, thereby can determine Vpp1 and Vpp2.

The above stated specification of exemplary embodiment of the present invention is provided for the purpose of explaining and illustrate.Its original idea is not exhaustive or limits the invention to disclosed exact form.Obviously, can carry out many modifications and modification for those skilled in the art.Select and illustrate that this exemplary embodiment is in order to explain better principle of the present invention and practical application thereof, therefore so that the others skilled in the art of the art can understand the various embodiment that the present invention is suitable for and predict the various modifications that are suitable for application-specific.Purpose is to limit scope of the present invention by claims and equivalents thereof.

Claims (11)

1. electrostatic charging device comprises:

Ring-type electrostatic charging band, it has electric conductivity, and described electrostatic charging band is arranged to have and the mobile state that is recharged the contacted predetermined contact area of body, and moves along the direction identical with the described moving direction that is recharged body;

A plurality of electrod assemblies, it comprises the first electrod assembly and the second electrod assembly at least, described a plurality of electrod assembly is arranged on the inside of described electrostatic charging band, and thereby described the first electrod assembly and described the second electrod assembly contact area that is arranged on described electrostatic charging band is squeezed in described being recharged on the body along the both sides of the moving direction of described electrostatic charging band with described electrostatic charging band, and described the first electrod assembly and described the second electrod assembly form respectively and allow in the described gap of discharging between body and the described electrostatic charging band that is recharged, and described each gap is respectively adjacent in the respective side of the contact area of described electrostatic charging band; And

Bias voltage applying unit, it applies the AC component to described the first electrod assembly and described the second electrod assembly respectively.

2. electrostatic charging device according to claim 1, wherein:

Described bias voltage applying unit to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

3. electrostatic charging device according to claim 2, wherein,

Described bias voltage applying unit applies described the first electrostatic charging bias voltage to described the first electrod assembly, and the AC component of described the first electrostatic charging bias voltage is equal to or less than the described surface potential of body that is recharged for the degree of tilt change point of described AC component.

4. electrostatic charging device according to claim 2, wherein,

Described bias voltage applying unit applies described the second electrostatic charging bias voltage to described the second electrod assembly, and the AC component of described the second electrostatic charging bias voltage exceeds the described surface potential that is recharged body for the degree of tilt change point of described AC component and drop on can be described the second electrod assembly and described being recharged in the scope of carrying out Uniform Discharge between the body.

5. electrostatic charging device according to claim 1, wherein,

Described the first electrod assembly and described the second electrod assembly are rotatable roller shape parts, and described electrostatic charging band is stretched on the described roller shape parts.

6. electrostatic charging device according to claim 2, wherein,

Described bias voltage applying unit has the operating environment judgment part for the decision operation environment, and described bias voltage applying unit changes the electrostatic charging bias voltage that is applied on each electrod assembly based on the judged result from described operating environment judgment part.

7. electrostatic charging device according to claim 1 also comprises:

Extruder member, thereby it pushes described a plurality of electrod assembly and forms described contact area and described gap towards the described body that is recharged, described gap comprises anteroclusion gap and the rear interocclusal clearance that is close to along the described respective side that is recharged the moving direction of body with described contact area

Wherein, described extruder member pushes described a plurality of electrod assembly so that described rear interocclusal clearance does not change substantially.

8. an image forms assembly, comprising:

Photoreceptor, it is as being recharged body; And

Electrostatic charging device according to claim 1, it is positioned to towards described photoreceptor,

Wherein, described image formation assembly is releasably attached on the image processing system main body.

9. image according to claim 8 forms assembly, wherein,

Described bias voltage applying unit to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

10. image processing system comprises:

Photoreceptor, it is as being recharged body; And

Electrostatic charging device according to claim 1, it is positioned to towards described photoreceptor.

11. image processing system according to claim 10, wherein

Described bias voltage applying unit to each described a plurality of electrod assemblies apply the electrostatic charging bias voltage that differs from one another so that the AC component that is applied to the first electrostatic charging bias voltage on described the first electrod assembly less than the AC component that is applied to the second electrostatic charging bias voltage on described the second electrod assembly, described the second electrod assembly is positioned at the downstream of described the first electrod assembly along the described moving direction that is recharged body.

Images